Crystal detector



y 1927' E, A. WIRIGHT CRYSTAL DETECTOR Filed Aug, 22, 1925 6 ii iai iiirgym 'glllla lih' 20 Irv/0292507 7 ass 6 M WW 14% QW Patented July 19,1927.

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tude modulated in accordance with the amplitude-of an impressed wave ofaudio frequency to thereby produce a unidirectional current ofcorresponding audio frequency variation which, by means of a telephone,may be caused to give audible signals. The object of my invention is toprovide a crystal support which may be conveniently manipulated tochange the position of the crystal with respect to the cat whisker, orother contact member in order to explore the surface of the crystal andquickly find a sensitive contact spot. and also to provide for avariation of the cat whisker upon the crystal. My invention is notlimited to the use of any particular variety of crystal, other than thatit is intended to be used with one,such as galena, in which sensitivespots lie in separated points which must be brought into contact withthe metallic contact member of the conductor carrying the signals inorder to rectify the radio frequency signals carried thereby, and it isparticularly useful in connection with crystals in which a niceadjustment of pressure of the contact member upon the crystal isimportant. My invention resides in the mechanical construction of thedevice which I have provided to accomplish the purposes mentioned, theessential elements thereof being more particularly pointed out in theappended claim defining my invention.

In the drawing, Figure 1 is a top plan view of the detector; and Fig.2'is a longitudinal section of the same in the plane indicated by thedotted line 2-2 of Fig. 1, looking in the direction indicated by thearrow.

Like reference characters indicate like parts in all the figures of thedrawing.

My crystal detector is constructed as a self-contained unit adapted tobe secured as a whole to a wall or panel of the'radio set in which it isemployed. Describing now the particular construction shown in thedrawing. the frame includes a base plate 1 e nipped with oppositebinding posts 2-2 w ich are threaded to engage nuts 3 by which the postsare secured to the base plate,

The binding post 4, it may here be stated,

is in electrical connection with the base plate 1 and the crystal, whilethe binding post 4 i is insulated from such parts and is inelectricaleonnection with the cat whisker.

The crystal 5 is mounted in any suitable manner in a rotatable holder 6pivoted on the base plate and formed with a peripheral gear 7 arrangedto mesh witha Worm 8 formed on a shaft 9 which is provided with a knob9" for turning it. In the present instance, the crystal is mounted bymeans of Woods metal 10 in a metal cup 11 which is removably secured inthe rotatable holder 6 by means of spring clips 6' secured to thelatter, to provide for change of crystals thus mounted.

The shaft 9 before mentioned is rotatably mounted in an ear 12 struck upfrom the base plate and a tubular flanged block 12 a cam disk 13 made ofnon-conducting material, such as bakelite. This disk is, arranged tocooperate with the contact arm 14 of a rocking lever 15 pivotallymounted in a bracket 16 which is non-conductively mounted on the base ofthe detector and electrically connected with the binding post 4". Thecat whisker 17, mounted on an arm 18 which projects from the rockinglever 15, is'arranged to make contact with the crystal non-axially oroff-center of its axis of rotation, and a spring 19 serves to maintainit in yielding contact with the crys tal when a lower portion of thedisk permits the cat whisker to rock towards the crystal. The distanceof the contact point from the axis of rotation may be varied by bendingthe cat whisker slightly, or may be attained byofisetting parts ofregular and symmetrical construction.

The binding posts 4-4 being properly connected in circuit, it is obviousthat by turnin the knob 9 the crystal will be very slowly rotated,.while the contact point of the cat whisker will be alternately raisedand lowered to var the pressure of the contact, averv precise andpermanent adjustment being thus attained. I claim:

.A crystal detector for radio apparatus comprising a frame, a rotatablecrystal holder and crystal mounted therein, a nonaxially. arrangedcontact member insulated from said holder and arranged to complete thedetector circuit through said crystal, and 10 said block bein e nippedwith a clamping 15 nut, whereby t e etector may be clamps to asupporting panel.

' ELTON A. WRIGHT.

